On the 30th of November a series of signals was commenced to be interchanged at night between the position of the transit instrument on Parks Hill and the highlands of the Aroostook.  These were continued at intervals whenever the weather was sufficiently clear until by successive approximations a station was on the 9th of December established on the heights 1 mile south of that river and on the meridian line.  The point thus reached is more than 50 miles from the monument at the source of the St. Croix, as ascertained from the land surveys made under the authority of the States of Maine and Massachusetts.  The measurements of the party could not be extended to this last point, owing to the depth of the snow which lay upon the ground since the middle of November, but the distance derived from the land surveys must be a very near approximation to the truth.  A permanent station was erected at the position established on the Aroostook heights and a measurement made from it due west to the experimental or exploring line of 1817, by which the party found itself 2,400 feet to the east of that line.

Between the 1st and 15th of December the observations were carried on almost exclusively during the night, and frequently with the thermometer ranging from 0 to 10 and 12 degrees below that point by Fahrenheit’s scale.  Although frequently exposed to this temperature in the performance of their duties in the open air at night, and to within a few degrees of that temperature during the hours of sleep, with no other protection than the tents and camp beds commonly used in the Army, the whole party, both officers and men, enjoyed excellent health.

During the day the tents in which the astronomical computations were carried on were rendered quite comfortable by means of small stoves, but at night the fire would become extinguished and the temperature reduced to within a few degrees of that of the outward air.  Within the observatory tent the comfort of a fire could not be indulged in, in consequence of the too great liability to produce serious errors of observation by the smoke passing the field of the telescope.  The astronomical observations were therefore always made in the open air or in a tent open to the heavens at top during the hours of observation, and without a fire.

On the 16th of December the tents were struck and this party retired from the field for the season, there being then more than 2 feet of snow on the ground.  To the unremitting zeal amidst severe exposures, and to the scientific and practical attainments of the officers, both civil and military, who served under the orders of the commissioner on this duty, he acknowledges himself in a great measure indebted for the progress that he was enabled to make, notwithstanding the many difficulties encountered.

Observations were made during portions of three lunations of the transit of the moon’s bright limb and of such tabulated stars as differed but little in right ascension and declination from the moon, in order to obtain additional data to those furnished by chronometrical comparisons with the meridian of Boston for computing the longitude of this meridian line.